Relative combination of an apex seal and a rotor housing in the rotary engine

ABSTRACT

A layer of Fe-O compound having the thickness of more than 0.1 mm is formed on a sliding surface of an apex seal made from a ferrous or nonferrous metal by the spraying treatment. The oxygen content in the Fe-O compound is ranging from 15.0 wt.% to 30.05 wt.%. A hard layer having the Hv hardness of more than 650 is formed on the sliding surface of the rotor housing. Both said apex seal and rotor housing are combined with each other, intending to improve the wear and scuffing resistances of the sliding surface.

United States Patent Sasame et a1.

[ RELATIVE COMBINATION OF AN APEX 3,061,525 10/1962Grazen.............................. 3,155,311 11/1964 Jones 3,155,31311/1964 Bentele................. 3,394,877 7/1968 Hantzsche et a1.3,731,941 5/1973 Mori et FOREIGN PATENTS OR APPLICATIONS 1,003,1189/1965 United Kingdom..........

Primary Examiner-C. J. Husar Assistant Examiner-O. T. Sessions Attorney,Agent, or FirmSughrue, Rothwell, Mion, Zinn and Macpeak [57] ABSTRACT Alayer of Fe-O compound having the thickness of more than 0.1 mm isformed on a sliding surface of an apex seal made from a ferrous ornonferrous metal by the spraying treatment. The oxygen content in theFe-O compound is ranging from 15.0 wt.% to 30.05 wt.%. A hard layerhaving the HV hardness of more than 650 is formed on the sliding surfaceof the rotor housing.

Both said apex seal and rotor housing are combined with each other,intending to improve the wear and scuffing resistances of the slidingsurface.

1 Claim, 2 Drawing Figures 6 8 3, m s ow r A a a 2 5 ll 5 S 7 1 3 E "3 72 a/ a 2 s 2 O0 H tm u 7 ICR007 7 T Khun d 4 "H1 1 7 .ta t n 0 .1l/ 2 Nah D-L m 2F3...0O m .mm a RU M S m H 2 m m maan 2. m .m H E U wmmw m mmmwm dMm 0 f a WW D m H H m m n P 1 MWZW M R dammn n 41 1 a 0 fl axd .B9 0 8 0 BE n TE mm8 J. 6 w n W. m N M e 0N m 3 6 .mw mwl e m 0h a 0 8.rT RI aaar. y 7n 1 5 mnnn m m w & p 5mm n TTNMNTA3 A "tr/7 R DE 2 ".8774 n 7 "81 T M 3 a 0 i9 SI Ml R 0 e N n .I.. .01 u L t n 03 C U T m .W d.1. F 0 V S e D. g S I E n S H D. U .m 0 H m mu m 2 n m .l. I mm B UHDUU 2 PATENTEDJUH 1 7 I975 FIG.

HUO

QZEDOI $0.5m m0 RELATIVE COMBINATION OF AN APEX SEAL AND A ROTOR HOUSINGIN THE ROTARY ENGINE BACKGROUND OF THE INVENTION This invention relatesto a relative combination of an apex seal and a rotor housing in therotary engine.

SUMMARY OF THE INVENTION An object of this invention is to increase thedurability of the rotary engine by imparting thereto the high wear andscuffing resistances.

Another object of this invention is to solve problems on the chattermark" which is considered to be resulted partly from a discontinuity ofthe lubrication between the apex seal and the rotor housing,

According to this invention. an apex seal made from a ferrous ornonferrous metal and having the sprayed layer of a Fe-O compound on thesliding surface which contains 150 30.05 Wt/Yr of oxygen and has thethickness of more than 0.1 mm is combined with a rotor housing having ahard layer of more than Hv 650 on the sliding surface. Hv hardnessstands for Vickers hardness.

The amount of oxygen in the Fe-O compound is closely connected with theself-lubrication of the apex seal, and accordingly restricted to theabove described range of 15.0 30.05 wt./(.

The thickness of the sprayed layer must be at least 0.1 mm. If thethickness of the sprayed layer is not more than 0.1 mm. the desiredservice life of the apex seal will not be expected. The upper limit ofthe thickness ofthe sprayed layer is determined by the results ofexperiments and the economical reason, and preferably 5 mm or less.

The hard layer to be formed on the sliding surface of the rotor housingmay be a hard Cr plated layer. or a Ni plated layer containing siliconcarbide or the like hard particles. and the Hv hardness of the hardlayer must be more than 650 as taking the wear resistance intoconsideration.

FIG. 1 is an enlarged photograph showing a microstructure of the sprayedlayer ofthe Fe-O compound in the apex seal, wherein the white zonesindicate the sprayed layer ofthe Fe-O compound containing oxygen and theblack zones indicate voids in the sprayed layer formed during thespraying treatment.

Such structure of the sprayed layer exhibits the excellent wearresistance and scuffing resistance due to the self lubricating propertyof the Fe-O compound. Besides, the voids in the sprayed layer causes theporous and oil impregnating structure. As the Fe-O compound is readilyconverted into drops during the spraying treatment due to the relativelylow melting point (about 1500C). the sprayed particles are mutuallyentangled to increase the strength of the sprayed layer itself.Accordingly, the acceleration of the abrasion of the apex seal and therotor housing by the peeled off particles is never caused.

Where the sliding surface of the rotor housing is hard, the combinationof the above said apex seal and the rotor housing brings outunexpectedly high wear resistance therebetween, and reduces the formingof the scuffing due to the self lubricating property and the oilimpregnating property of the sliding surface of the apex seal even ifthe discontinuity of the lubrication exists between the apex seal andthe rotor housing, thus resulting in the prevention of the chatter mark.

BRIEF EXPLANATION OF THE DRAWINGS FIG. I is an enlarged photographshowing a microstructure (magnitude of a sprayed layer of Fe-O compoundformed on the sliding surface of the apex seal. and

FIG. 2 is a graph showing the wear resistance of the sliding surface forthe conventional combination of the apex seal and the rotor housing andthat for the combination according to this invention.

PREFERRED EMBODIMENTS OF THIS INVENTION Now, some examples of thisinvention will be described with reference to the drawings.

EXAMPLE I A Fe-O compound containing 27.6 wt.% of oxygen wasplasmasprayed on a sliding surface of an apex seal made from the castiron (JIS FC-25) to form the layer of 1 mm thickness. The Hv (30)hardness of the resultant sprayed layer was 700.

The spraying conditions were as follows:

spraying gun; Meteco 3M type plasma spraying gun N gas pressure; 50lb/in N gas flow rate; ft lhr.

H gas pressure; 50 lb/in electric current applied; 500 A sprayingdistance; 4 inch.

On the other hand. the hard Cr plating was applied to a sliding surfaceof a rotor housing made from Al to form the layer of 0. l 5 mm. The Hvhardness of the hard Cr layer was 950. The conditions for the hard Crplating treatment were as follows:

current density; 60 A/dm bath temperature; 60C

bath composition; chromate anhydride 250 g/liter and sulfuric acid 2.5g/liter The apex seal and the rotor housing thus treated were combinedwith each other, and the combination was subjected to the wearresistance test in the actual engine.

specification of the engine used;

I. type;

2. total exhaust volume;

3. maximum output;

4. maximum torque test conditions;

I. rotating number; 2680 rpm. 2. boosting pressure; 35() mm.Hg 3.running time; 50 hr.

In order to compare the properties of the combination of the apex sealand the rotor housing according to this invention with that of theconventional combination. the same wear resistance test as describedabove was subjected to the combination of the same rotor housing in theExample 1 and an apex seal made from a cast iron composed of total C3.6%, Si 2.8%. Mn 0.7%, Ni 0.7%, Cr 0.6%, M0 1.1%, Cu 1.0% and V 0.2%and having the HRB hardness as determined by the Rockwell B scale of110, under the same testing conditions in the Example I.

The test results are shown in the FIG. 2, wherein No. 2 is the testresult for the combination according to this invention and No.1 is thatfor the conventional combination.

It will be apparent from the PK]. 2 that the wear amount of apex sealNo.2 is only about 1/7 of that of the apex seal No.1, and the wearamount of rotor housing No.2 is only about 1/5 of that of rotor housingNo.1 accordingly this invention has the excellent durability.

The chatter mark is not observed in the combination according to thisinvention.

Then, the scuffing resistance test was carried out using the rotary wearresistance tester. A specimen having the sprayed surface layer wasthrusted on a turn table which was rotated supplying the lubricating oilbetween the surface layer of the specimen and the upper surface of theturn table. The load to thrust the specimen on the turn table wasgradually increased at every one hour to detect the limit load to causethe scuffing. testing conditions:

1. test specimen No.l;

obtained by plasm-spraying Fe-O compound containing oxygen 27.6% on thesurface of a cast iron (JlS FC25) to have the thickness of 1 mm and theHv (30) hardness of 700.

2. test specimen No.2;

composed of total C 3.6%, Si 2.8%, Mn 0.7%. Ni 0.7%, Cr 0.67:, M 1.1%.Cu 1.0% and V0271, and having the HRB hardness of 110.

3. turn table;

made from the cast iron (JlS FC-ZS) and the hard Cr plating is appliedon the surface to have the Hv hardness of 950,

'4. temperature of the lubricating oil; 80C.

5. rate of feeding the lubricating oil; 0.6 l/hr.

6. lubricating oil;

Daphni oil number 50% and lamp oil 50%.

7. running time:

every 1 hr. for the load 50 kg/cm l00 kg/cm and l50 kg/cm and 200 kg/cmThe No.1 specimen was observed to cause the scuffing by the load of 200kg/cm whereas the No.2 specimen caused the scuffing at the load of only50 kg/cm It will be understood from this test result that the sprayedlayer of this invention exhibits the high resistance to the scuffingunder the high compression.

The base metal of the apex seal is not restricted to the cast iron. butmay be Al, Cu or the like nonferrous metals.

While this invention has been described with reference to particularembodiments thereof, it will be understood that the numerousmodifications may be made by those skilled in the art without actuallydeparting from the scope of the invention.

Therefore. the appended claim is intended to cover all such equivalentvariations as coming within the true spirit and scope of the invention.

What is claimed is:

l. A combination of an apex seal and a rotor housing in a rotary engine,wherein said apex seal is made from ferrous or nonferrous metal andhaving more than 0.1 mm of the sliding surface layer thereof formed byspraying Fe-O compound containing oxygen 15.0 30.05 weight and saidrotor housing has a hard plated sliding surface having the Hv hardnessof more than 650.

1. A COMBINATION OF AN APEX SEAL AND A ROTOR HOUSING IN A ROTARY ENGINE,WHEREIN SAID APEX SEAL IS MADE FROM FERROUS OR NONFERROUS METAL ANDHAVING MORE THAN 0.1 MM OF THE SLIDING SURFACE LAYER THEREOF FORMED BYSPRAYING FE-O COMPOUND CONTAINING OXYGEN 15.0 - 30.50 WEIGHT %, AND SAIDROTOR HOUSING HAS A HARD PLATED SLIDING SURFACE HAVING THE HV HARDNESSOF MORE THAN 650.